You are implying that you believe them to be incompetent since otherwise you would not expect evidence in this instance. They also haven't provided independent verification of their claims - do you suspect them of lying as well?
How do you explain the specific score that was achieved if as you suggest the LLM simply copied the answer directly?
Either they have proof that their LLM is not cheating or they don't. The linked post does not provide evidence that the LLM is not cheating. I don't have to explain anything on my end b/c my claim is very simple & easily refuted w/ the proper evidence.
How do you explain the specific score that was achieved if as you suggest the LLM simply copied the answer directly?